1. Field of the Invention
The invention relates to optical lenses and lens systems in general and to cylindrical lenses and cylindrical lens systems such as are used in beam shaping of the light from high power semiconductor diode lasers and corresponding arrays.
2. Description of Related Art
A cylindrical lens is understood as a transparent optically refracting body having at least one bounded free surface. The real or virtual combination point of beams entering in an axially parallel fashion is understood as the focal point.
Devices for beam shaping the light of high power lasers are conventionally constructed in a complicated fashion using multilens refractive systems (for example lens arrays and/or prism arrays): see, for example, DE 195 00 513 or else DE 198 46 532 and EP 0 961 152. These optical systems serve the purpose of carrying out beam shaping by largely retaining the optical quality of the laser diode emitter radiation, in particular of circularizing the beam cone between the so-called fast axis and slow axis.
Furthermore, PCT/EP02/03283 proposes linear prism arrays for correcting the light emanating from a laser array. The aim in this case is to use prisms of respectively different tilt to compensate a lateral offset, known as “smile”, of individual lasers in the case of which the respective light exit surface of the individual laser is situated not on a straight line but on a curved line.
Lens arrays and prism arrays are generally difficult to fabricate and have, between the respective prisms, stepped lateral surfaces that are disadvantageous for the propagation of light by reflection. Further multiple prism arrangements are also known from U.S. Pat. No. 6,421,178 B1.
WO 00/19248 describes a biconcave microcylindrical lens system in which at least two aspheric surfaces are to be produced with high accuracy. It is known from the standard textbook “High-Power Diode Lasers” by R. Diehl, Springer (2000), that optical materials of high refractive index (generally >1.7) must be used in conjunction with aspheric surfaces for the purpose of exact fast-axis collimation (residual divergence <5 mrad) of diode laser emitters or emitter arrays by means of purely refractive optics. Not only is the high outlay on production of aspheric surfaces adjusted relative to one another disadvantageous in such systems, so also is the difficult exact mounting, for example, in the exact alignment relative to a stationary light source. It is proposed here for the purpose of simplifying the mounting to fit spacers that prescribe a defined spacing from a reference plane. However, what is disadvantageous here is that even a slight deviation in the refractive power and/or the dimensional accuracy of the lens owing to the manufacturing tolerances would also respectively require different spacings, and this could be taken into account only with great effort.